Air filter



1965 A. e. BRAINERD, JR., ETAL 3,164,456

AIR FILTER Filed Jan. 25, 1962 INVENTORS ALFRED G- BRAINERD, JR. GUY E-MORGAN ATTORNEYS United States Patent 3,164,456 AIR FILTER Alfred G.Brainerd, Jr., 6913 Glenwood, and Guy E. lvlorgan, 5701 Belmont, both ofEast St. Louis, Ill.

Filed Jan. 25,1962, Ser. No. 168,780

6 Claims. (Cl. 55-590) This invention relates to an air filter and moreparticularly to the combination of a frame and a corrugated filteringmedium, such as Urethane foam, supported thereby.

In general, the filter comprises an inner frame including flanged sideplates and doubled over end plates interlocked with the side plateflanges. There are two rows of equally spaced rods alternately spacedbetween the end plates and releasably fastened to the side plates. Asheet of Urethane foam is passed alternately about the rods and issecured to each end plate. An outer frame comprising channel memberswelded, riveted, or screwed together surrounds the inner frame.

One of the significant features of the invention is its economicconstruction and ease of assembly. The rods which are releasablyfastened to the side plates automatically position the side platesrelative to one another and thereby lock the end plates in place becausethe end plates interlock with the flanges on the side plates. Hence theinner frame is self-locking and its assembly requires no specialtooling. Even the outer frame is of simple construction. It comprises aone piece standard channel member that is notched and bent to arectangular shape and is fastened together at a single closing corner.This corner fastening may be a screwed flange connection, riveting,welding, or the like.

The Urethane foam sheet is fastened to the outer sides of the endplates. Consequently, a portion of the Urethane foam sheets is pressedbetween the end plates and the adjacent outer frame channel member.Strips of Urethane foam sheet are also disposed between the inner frameside plates and the opposing outer frame channel members. As a result,there is the Urethane foam filtering media at all points within theouter frame channel members so that no air can pass through the filterwithout being filtered.

A principal object of this invention is to provide a corrugated Urethanefoam filter including a self-locking frame for supporting a sheet ofUrethane foam.

Another object of the invention is to provide a corrugated Urethane foamfilter including a frame for supporting a Urethane foam sheet that iseasy to assemble and is very economical in cost.

Still another object of the invention is to provide a corrugatedUrethane foam filter that has an inner frame for supporting a sheet ofUrethane foam and an outer frame by which the filter is installed withmeans to assure filtering of air at any point within the outer frame.

Another object of the invention is to provide a dry media filter ofsufiicient efliciency to be practical and to increase the total surfacearea thereby increasing dust holding capacity and reducing staticpressure drop across the filter.

Other objects will appear from the description to follow.

In the drawings:

FIGURE 1 is an isometric view of the filter on a reduced scale;

FIGURE 2 is a fragmentary view in section taken along the line 22 ofFIGURE 1;

FIGURE 3 is a view in section taken along the line 3-3 of FIGURE 1;

FIGURE 4 is a fragmentary and exploded corner view of the inner andouter frames also showing the rods and showing a side sheet of Urethanefoam; and

1 FIGURE 5 is a fragmentary view in section similar to the right side ofFIGURE 2, but showing an alternate form of the invention.

Referring now to the drawing, the filter comprises an inner frame 10which supports a corrugated sheet of Urethane foam 11 in a manner to bedescribed, and an outerframe 12. The inner frame 10 i ncludes a pair ofside plates 13, each of which has two end flanges 14 of smaller widththan the side plates 13. These end flanges 14 have bent-over upper andlower tabs 15 which project at right angles to the plates 13. The innerframe 10 also has a pair of doubled-over end plates 16 which are not aswide as the side plates 13. As shown in FIGURE 4, the end plates 16 havean inner wall 17 and bent-over longitudinal flanges 18 spaced outwardlyfrom the inner wall 17. There is a space between the flanges 18 and theinner wall 17 of the end plates, and the end flanges 14 fit within thatspace to support the end plates 16. There is also a space between theedges 19 of the longitudinal flanges 18.

There are a plurality of pairs of axially aligned crimped retainers 20and 21 which project from the inner face of each side plate 13. Theseretainers 20 and 21 support two rows of rods 22 and 23. The rods 22 andthe rods 23 alternate with one another along the side plates 13. Each ofthe rods 22 has bent-down ends 24 that fit within a pair of retainers 20and 21 on each side plate 13. Each of the rods 23 has bent-up ends 25that also fit within a pair of retainers 20 and 21, but from theopposite direction to that of the ends 24. These rods 22 and 23, whenengaged within their respective retainers 20 and 21, hold the sideplates 13 together and thereby hold the flanges 15 within the ends ofthe end plates 16.

The ends 24 on the rods 22 and the ends 25 on the rods 23 are initiallybent to angles of somewhat greater than Therefore, when the rod ends arein place in the retainers 20 and 21, they are biased outwardly againstthe side plates 13. Since the angles of the ends 24 to the rods 22 and23 are greater than 90, they are held in the retainers 20 and 21 byfriction while the Urethane foam is installed. Also, they bow outwardlysomewhat, and thereafter, when the Urethane foam sheet is put on, itdraws the rods 22 and 23 intostraight lines. If the rods were notinitially bowed outwardly, the foam sheet, when added would how the rodsinwardly.

The Urethane foam 11 is in'the form of a flexible sheet; As shown inFIGURE 2, the sheet of Urethane foam 11 is wrapped alternately about therods 22 and 23. The opposite ends 27 of the Urethane foam sheet 11 arepassed around an edge of the end plates 16, and through the spacebetween the edges 19 of the flanges 18 whence they are wedged into thespace between one of the flanges 18 and the opposing inner wall 17. Withthe Urethane foam sheet 11 in the installed condition illustrated inFIGURE 2, it holds the rods 22 and 23 in place within their respectiveretainers 20 and 21.

Finally, there is the outer frame 12. The outer frame comprises achannel member 28 notched and bent to four sides 29, 30, 31 and 32 asillustrated. This leaves two free ends of the channel at one corner 33.At this corner 33, one of the channel ends has a flange 34 on it whichis fastened to the other channel end by one or more screws 35. The foursides of the channel member 28 fit around the inner frame 10 with theupper and lower flanges 36 confining the side plates 13. Two of thechannel sides 29 and 31 press the ends 27 of the Urethane foam sheet 11against the flanges 18 of the end plates 16. There are. two strips 37 ofUrethane foam sheet between the channel sides 30 and 32 and the sideplates 13.

The ends 27 of the Urethane foam sheet 11 and the separate sheets 37 ofUrethane foam assure that no air a can pass between the inner and outerframes and 12 without also passing through the filtering medium. Fromthe foregoing description of this filter, it is evident that itcomprises only a few parts and yet effectively holds the Urethane sheet11in a' corrugated condition. The advantages of the corrugated Urethanefoam are that it thereby presents a greater surface area for filteringair and thus performs its job more effectively.

The .ease of assembly of this filter should be evident from theforegoing description. The flanges 15 of the side plates 13 are insertedinto the ends of the doubledover end plates 16. Then the ends 24 and ofthe rods 7 'other end plate 16; The Urethane foam sheet 11 retains therods 22 and 23 within their respective retainers 2t) and 21. Thedoubled-over flange construction of the end plates 16 holds the ends 27of the Urethane foam sheet 11 firmly in place. Finally, the channelmember 28 (preceded by the positioning of two Urethane foamsheets 37) isplaced around the inner frame 10 and is fastened together at its closingcorner 33 by the screw 35. a

The parts of the filter are self-locking. The ends 27 of the Urethanefoam sheet 11 are locked within the spaces between the flanges 18 of theend plates 16 and between one flange 18 and the opposing inner wall 1'7.The Urethane foam sheet 11 holds the rods 22 and 23 in place. The rods22 and 23 hold the side plates 13 and the end plates 16 in place.

A slightly modified form of the invention is shown in FIGURE 5. In thismodification, the side plates 13 are the same as those alreadydescribed; so are the rods 22 and 23. So is the outer frame 12 and so isthe Urethane foam sheet 11. However, instead of the doubled-over endplates 16, the filter of FIGURE 5 has straight plates 50 that are weldedor screwed to the side plates 13. Sharp tabs 51 are bent away from theend plates 50. The end 27 of the Urethane foam sheet 11 is bent aboutwedge of the end plates 50 and is hooked onto the sharp tabs 51. Theadditional Urethane foam sheets 37 are also used with the filter ofFIGURE 5 so that no air can pass through the filter without beingfiltered. I

Various changes and modifications may be made within the apparatus ofthis invention as will be readily apparent to those skilled in the art.Such changes and modifications are within the scope and teaching of thisinvention as defined by the claims appended hereto.

What is claimed is:

1. A filter comprising an inner frame and an outer frame, the innerframe comprising side plate members and end plate members, a pair ofparallel rows of rods fastened to the side plate members and extendingtherebetween, a sheet of flexible Urethane foam having. its endsfastened to the outer side of the end plate members and being woundabout alternate ones of the rods to dispose the Urethane foam in acorrugated sheet, the outer frame having two parallel channel sides andtwo parallel ends opposite the side plate members and the end platemembers respectively, the channel ends compressing the ends of theUrethane foam sheet between them and the end plate members, the rodshaving means to hold the side plate members in position relative to theend plate members, and flanges on the ends of the side plate members forinterlocking with the end plate members.

2. The filter of claim 1 with separate sheets of Urethane foam pressedbetween the side plate members and the opposing outer frame channelsides;

3. The filter of claim 1 wherein the rods are releasably positioned byretainers in the side plate members and the Urethane foam sheet holdsthe rods within their respective retainers.

4. A filter comprising a frame having side plate members and end platemembers, the side plate members having two rows of rod retainers andalso having flanges at their outer ends, the end'plate members havingdoubledover flanges along their upper and lower edges, a pair of rows ofrods having bent ends extended within the retainers, and a sheet of foamfiltering medium having two opposite ends each clamped between an endplate member and an end plate flange and being wrapped alternately aboutthe rods, the rods being held in the retainers by the foam sheet and theside and end plate members being held together by the rods.

5. The filter of claim 4 wherein the bent ends of the rods are biasedoutwardly against the side plates.

6. The filter of claim 5 wherein each rod end is received within a pairof axially aligned retainers.

References Cited in the file of this patent UNITED STATES PATENTS2,074,294 Woodruif Mar. 16, 1937 2,415,579 Dahlman Feb. 11, 19472,999,562 Letchtenberg' Sept. 12, 1961 FOREIGN PATENTS 3,863 Australiaept.29, 1932

1. A FILTER COMPRISING AN INNER FRAME AND AN OUTER FRAME, THE INNERFRAME COMPRISING SIDE PLATE MEMBES AND END PLATE MEMBES, A PAIR OFPARALLEL ROWS OF RODS FASTENED TO THE SIDE PLATE MEMBERS AND EXTENDINGTHEREBETWEEN, A SHEET OF FLEXIBLE URETHANE FOAM HAVING ITS ENDS FASTENEDTO THE OUTER SIDE OF THE END PLATE MEMBERS AND BEING WOUND ABOUTALTERNATIE ONES OF THE RODS TO DISPOSE THE URETHANE FOAM IN A CORRUGATEDSHEET, THE OUTER FRAME HAVING TWO PARALLEL CHANNEL SIDES AND TWOPARALLEL ENDS OPPOSITE THE SIDE PLATE MEMBERS AND THE END PLATE MEMBERSRESPECTIVELY, THE CHANNEL ENDS COMPRESSING THE ENDS OF THE URETHANE FOAMSHEET BETWEENTHEM AND THE END PLATE MEMBERS, THE RODS HAVING MEANS TOHOLD THE SIDE PLATE MEMBERS IN POSITION RELATIVE TO THE END PLATEMEMBERS, AND FLANGES ON THE ENDS OF THE SIDE PLATE MEMBERS FORINTERLOCKING WITH THE END PLATE MEMBERS.